Forwarding jet



.Feb. 7, 1967 A. P. COPE ETAL vFORWARDING JET 5 Sheets-Sheet 1 FiledJan. 15, 1965 Feb. 7, 1967 I COPE L I 3,302,237

FORWARDING JET 3 Sheets-Sheet 2 Filed Jan. 15, 1965 Feb. 7, 1967 A. P.COPE ETAL 3,302,237

FORWARDING JET 7 Filed Jan. 15, 1965 v 5 Sheets-Sheet 3 w w q 9 w w J pu;

. v wW/V/fl/fl/ ///////////////////////////4@ mm m N H W &

United States Patent 3,302,237 FORWARDING JET Andrew I. Cope,Wilmington, DeL, Robert Meagher, Wallingford, Pa, and Dimitri Zafiroglu,Wilmington, Del, assignors to E. I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware Filed Jan. 15, 1965, Ser.No. 425,839 5 Claims. (Cl. 181) This invention relates tofilament-forwarding jet devices in particular to jet devices whichutilize the tension exerted by a high-velocity gas stream to effectforwarding of the filaments. 1

Jet devices have been used in the textile industry for many years toeffect drawing, texturing, stripping, annealing, crimping, bulking,interlacing, etc. of synthetic yarns. In most cases the filamentpassageways of these prior devices have had round cross sections.Recently jet devices with slot-shaped cross sections have beendeveloped, as exemplified by Clauss'en and Meyer, US. Patent 3,055,080,issued September 25, 1962, and Dyer and Gallagher, US. Patent 3,081,951,issued March 19, 1963. The slot jet devices described in these patentswere designed to impart bulk, fiuffing, and filament entanglement bymeans of turbulent gas streams and accordingly they are not suitable forforwarding'a strand of filaments while the filaments are maintainedsubstantially free from entanglement.

Forwarding of filaments with a minimum of entanglement and bunching isrequired in a recently developed process for the production of nonwovenwebs from continuous synthetic organic filaments. In this processinvolving an integrated filament-spinning, orientation, and laydownoperation such as described in British Patent 932,482, a multi-filamentstrand of continuous filaments is electrostatically charged andforwarded toward a receiver, the filaments are allowed to separate dueto the repelling effects of the applied electrostatic charge, and arethen collected on the receiver as a random nonwoven web which isessentially free from filament aggregates. Jets are ideally adapted foruse as filament-forwarding devices in this process, since the forwardingtension exerted by the jet can be used to direct the filaments towards areceiver and can then be rapidly released thus permitting the filamentsto separate from each other due to the electrostatic charge. Round jetsare suitable for this purpose when handling a comparatively small numberof filaments, for example, up to 200 per jet, but with the largerfilament strands, up to 1000, as are required for economical commercialoperation, round jets are less satisfactory.

In large-scale commercial operation of the above-described web laydownprocess, wherein the output from several spinnerets is utilized, it hasbeen found that mechanical drawing of the freshly-spun syntheticfilaments with draw rolls is desired in order to obtain uniform filamentproper-ties from spinneret to spinneret and, therefore, throughout thenonwoven web. In order for a rolldrawing system to operate properly, itis necessary to provide a tension on the filaments leaving the last drawroll to strip the filaments from the roll and prevent slippage offilaments on the draw roll. While draw jets with a round cross sectionare capable of producing the required tension, they do not conformgeometrically to the ribbon-shape of the filament strand as it leavesthe draw roll. With large filament strands, for example, thosecontaining several hundred filaments in ribbon form, this lack ofconformity of the jet structure to the strand geometry causes bunchingof the filaments with a resulting ropiness in the nonwoven web. However,mere conformity of the jet structure to the ribbon shape of the3,302,237 Patented Feb. 7, 1967 "ice filament strand does not meanacceptable performance in the laydown process of the above-describedpatent, and it has been found necessary to develop a jet of novel andhighly specialized design.

The complex nature of this design problem will be readily apparent fromthe seemingly mutually incompatible performance requisites of suitablejet devices. Thus, not only must the jet be capable of impartingadequate tension (greater than about 0.10 g.p.d.) to the filament strandas it enters the jet, it must perform the following additionalfunctions: 1) aspirate suflicient gas to allow filament stringup andrestringing of broken filaments; (2) maintain a uniform velocity-profilethroughout the jet over a range of operating gas pressures and flows,thereby maintaining the filaments in a spread configuration; and (3)forward the filaments while maintaining a the filamentsv after thedraw-roll operation, but it makes further demands on the performancecharacteristics of the jet. Thus aspiration at the filament entrance tothe jet is required, but it is preferably maintained as low as possibleto minimize dilution of the hot relaxing gas.

3 As the poly(ethylene terephthalate) filaments approach relaxationtemperatures (about to C.), it is desired that the tension on thefilaments be decreased to a level of less than about 0.010 g.p.d., thuspermitting the filaments to relax, while still being sufficient toadvance the filaments with excellent separation.

It is the purpose of this invention to provide a jet device forforwarding filamentary materials with a minimum of filamententanglement.

It is another purpose to provide a jet device which can handle largestrands of continuous filaments in ribbonlike form.

It is still another purpose to provide a jet device in which a uniformgas-velocity profile is maintained throughout the jet.

An additional purposeis to provide a jet device which can be used toheat-relax -poly(ethylene terephthalate) filaments while they are beingadvanced toward a receiver on which they are collected as a randomnonwoven web.

These and other purposes are attained in accordance with this inventionby providing a filament-forwarding jet device having a filamentpassageway with a generally rectangular cross section and through whichthe filaments pass in essentially straight-line travel along thecenterline of the device. The jet housing has mounted therein afilament-entrance member and an effuser member, as described more fullybelow.

The jet device comprises two filament-entrance plates terminating in lipportions, two eifuser plates, and two end plates. The filament-entranceplates are placed adjacent each other so as to form, in cooperation withthe end plates, the filament-entrance member of the jet device. Theeffuser plates are so designed and placed adjacent each other as toform, in cooperation with the end plates,

a mixing section, throat opening, effuser section and filament exit ofthe jet device. From immediately below the lip portion of thefilament-entrance plates, the filament passageway converges to thethroat opening, thus constituting the mixing section. The effusersection of the filament passageway diverges from the throat opening tothe filament exit. The lips of the filament-entrance plates extend intothe mixing section and coact with the effuser plates to form two nozzleopenings having a width at the narrowest point of from 0.006 in. (0.015cm.) to 0.020 in. (0.051 cm.) and through which high-velocity gas may befed into each side of the filament passageway at the mixing section. Thethroat opening of the filament passageway has a width of from 0.021 in.(0.053 cm.) to 0.08 in. (0.20 cm.), with the proviso that the width ofthe throat opening is at least 3.5 times the width of each nozzleopening. The filament-entrance plates and the effuser plates furthercoact to form plenum chambers leading to the nozzle openings. Inlets areprovided to supply gas under pressure to the plenum chambers. The endplates coact with the filament-entrance plates and elfuser plates toclose the sides of the filament passage-way, the nozzle openings and theplenum chambers. They also hold the two filament-entrance plates and twoetfuser plates in the desired relationship to form the filamentpassageway.

The invention will be further understood by reference to the drawings inwhich:

FIGURE 1 is a top view of a jet device of this invention;

FIGURE 2 is a cross-sectional view of the jet on line AA of FIGURE 1;

FIGURE 3 is a side view of the jet of FIGURE 1;

FIGURE 4 is an end view of the jet of FIGURE 1;

FIGURE 5 is a side view of the top portion of the filament passageway ofthe jet on line BB of FIGURE 1, With a part of the nozzle plate cut awayto show the top edge of the effuser plate;

FIGURES 6 and 7 are detailed cross-sectional views of two embodiments ofthe filament entrance, mixing section, and nozzle openings of the jetsof this invention;

FIGURE 8 is a cross-sectional view of a jet of this invention having analternative design of the filamententrance plates and effuser plates.

Referring to FIGURES 1 and 2, the slotshaped filament passageway isshown as being formed in the filament-entrance member byfilament-entrance plates 1 and in the effuser member by effuser plates2. The filament passageway consists of filament-entrance section 3having an inlet for filaments and aspirated air, and an exit into themixing section 4, throat opening 5, effuser section 6, and filament exit7. The lips 8 of the filament-entrance plates coact with the upper endsof the effuser plates to form nozzle openings 9 on both sides of thefilament passageway, as shown in greater detail in FIGURES 6 and 7. Thefilament-entrance plates and elfuser plates also coact to form plenumchambers 10 which are provided with inlets 11 for supplying gas underpressure. Thermal insulation may be attached to the plenum side of theefluser plates in the area opposite inlet 11 to minimize formation ofhot spots by impingement of highvelocity, hot inlet gas. End plates 12cooperate with the filament-entrance plates and the effuser plates toclose the sides of the filament passageway, the nozzle openings and theplenum chambers and to hold the filament-em trance and efi'user platesin the desired relationship to form the filament passageway. FIGURE 4shows a suitable design for the end plates. The filament entrance platesare attached to the end plates by means of scerws 13 and the efifuserplates are attached by means of screws 14.

Notches 15 in the end plates are provided to permit ready attachment ofjet extensions, diffusers or relaxing chambers at the filament exit. Theends of the elfuser plates in FIGURE 2 are ideally suited for additionof jet extensions, while those in FIGURE 8 are adapted to receive adiffuser having curved side plates to spread the ribbon of filamentarymaterial, or a relaxing chambers, for example, as taught in the patentto Cope US. 3,156,752 but modified to have its filament passagewayconform to the slot-shape of the filament passageway of the jet devicesof this invention.

Adjustment of the relative position of the filamententrance plate andeffuser plate is made by means of set screws 16 acting on pin 17, and bymeans of set screws 18. (See FIGURES 2 and 3.) Screws 16 are used toslide the effuser plate relative to the filament-entrance plate andthereby vary the width of the nozzle opening while adjustment of screws18 imparts a rocking move ment to the filament-entrance plate andthereby provides for adjustment of the nozzle opening so that its Widthis uniform throughout. In this manner the jet is adjusted to give auniform gas-velocity profile. A seal 19 is provided to eliminate gasleakage from the plenum chamber. Screws 20 are then tightened to holdthe elfuser and filament-entrance plates after the nozzle opening hasbeen properly adjusted.

The maintenance of a uniform gas-velocity profile is of extremeimportance to the proper functioning of the jet devices of thisinvention. Dirt particles or any other extraneous materials in thenozzle opening will disrupt the uniform profile and give inferiorresults such as entrangled or bunched filaments. In the preferred jetdevices of this invention, an additional structural feature is utilizedto maintain a uniform velocity profile over a range of operatingpressures of the gas supplied to the plenum chambers. This feature isillustrated at R in FIGURE 5 where the side of the lip portion of thefilament-entrance plates is relieved so that it does not contact the endplate. This relief, which need only be of the order of 0.0001 to 0.0002in. (0.0002 to 0.0005 cm.) and preferably is as low as possible to avoidexcessive gas leakage between the lip and end plate, permits the entirelength of the lip to deflect uniformly under the force resulting fromthe the pressure differential from one side of the lip to the other.Thus, the adjustments of the nozzle openings for uniform flow hold overa wide range of flows (for example, 0 to 50 s.c.f.m.; 0 to 1400liters/min). The relief permits the entire lip to deflect as acantilever beam with a built-in base. Without the relief, the sides ofthe lip are not free to deflect while the middle portion does deflect.This causes the nozzle opening to vary across the length of the openingas the pressure and temperature are changed and gives a nonuniformgas-velocity profile. The sides of the etfuser plates at the ends wherethey coact with the lips to form the nozzle openings, can also berelieved as indicated at R in FIGURE 5 to eliminate nonuniformdeflection.

FIGURE 8 illustrate-s an alternative design for the filament-entranceplates and etfuser plates. In this design, the filament-entrance plateis fastened to the top portion 21 of the elfuser plate by screws 22.

The geometry of the nozzle openings and the mixing section and throatopening of the filament passageway is shown in FIGURES 6 and 7. In thesefigures, a is the angle which that surface of the efluser plate whichforms one wall of the nozzle opening makes with the centerline of thejet. [3 is the angle which the effuser plate makes with the centerlineof the jet below the nozzle opening. 7 is the angle which that surfaceof the lip of the filamententrance plate which forms one surface of thenozzle opening makes with the centerline of the jet. a-y represents theconvergence angle of the gas passageway leading to the nozzle opening.The convergence angle of the filament passageway from the mixing zone tothe throat opening is 2,6. Alternatively, 5 can be zero, in which casethe convergence angle of the filament passageway is 20:.

In the design of the optimum jet device for use in forwarding filamentswithout filament entanglement, the significant performance criteria are(1) the amount of high pressure (primary) gas used by the jet; (2) thetension applied to the filaments, and (3) the level of aspirated(secondary) gas. The consumption of primary gas is of importance becausehigh gas flows are detrimental to the quality of the nonwoven web beinglaid down. Moreover, high gas flows are costly, particularly when heatedgas is used in the jet to effect the heat-relaxation of the filaments.The tension applied to the filaments should be sufficient to preventtheir slipping on the draw rolls and to strip them from the rolls. Thetension should also be controlled so that heat-relaxation can beeffected if desired.' The aspirated gas should be at a level sufficientto provide for string-up of the filaments at the startup of the processand for self-stringing of broken filaments when needed; but is should beat the minimum needed for those purposes, particularly when the primarygas is heated, in order to avoid excessive cooling of the primary gas.The effects of the dimensions of the jet devices of this invention onthe above performance criteria are described in the following sections.These remarks apply to jets 3 to 8 in. (7.6 to 20 cm.) wide.

It is preferred that the length of the filament-entrance member be assmall as possible, not over 1.0 in. (2.5 cm.), to decrease the pressuredrop in the section and improve the suction of the aspirated gas. Owingto construction geometry, the minimum usable length is about 0.5 in.(1.3 cm.) A length of about 0.6 in. (1.5 cm.) is preferred.

In the context of this application the term width applies to the narrowdimension of the cross section of any passageway, perpendicular to theaxis of the passageway.

The width of the filamententrance-member passageway should be reduced toa minimum to reduce the distance from the filament-entrance plate lip tothe jet centerline, thereby minimizing the velocity drop of the highpressure air from the lips to the filaments and obtaining more efficientgenerationof tension on the filaments. As the width of thefilament-entrance-member passageway is decreased, there is asimultaneous increase in pressure drop along the passageway andconsequent decrease in aspiration. These are both small and can beignored, however, because of the shortness of the length of thefilament-entrance member. The minimum width of the passageway isdictated by the process-operability considerations and is about 0.015in. (0.038 cm.). Widths above 0.030 in. (0.076 cm.) produce poor resultsin efficiency of gas utilization.

The thickness of the lips of the filament-entrance-plate should be heldat a minimum for the same reasons indicated above for the width of thefilament-entrance member passageway. The minimum value of the lipthickness to permit reasonably rigid beam sections is 0.010 in. (0.025cm.). Thinner lips are fragile and, moreover, their deflections underthe forces resulting from differential gas pressures are large and verydiflicult to maintain uniform. Similar considerations apply to the lipangle 7. This angle should be minimum to reduce the angle of the axis ofthe gas stream emerging from the nozzle opening with the centerline ofthe jet to the lowest possible value. This minimizes the energy wastedue to velocity components perpendicular to the filaments. Angle 7,however, should not be reduced below 10 since the beam section of thelips would then be too weak for a long span and would lead to excessivedeflection.

The effuser plate angle a should be minimum for the same reason ashaving angle 7 minimum. Jets in which the convergence angle (u'y) of thegas passageway leading to the nozzle openings is 2 are suitable, thus anoperable value for a is 12. It is essential, however, that the nozzlesdirect air or other fluid at the moving filament bundle at an angle ofless than 16 to ensure nonentanglement of the filaments with resultingnonuniform sheets.

The convergence angle (2,8) of the filament passageway from the mixingsection to the throat opening and the length of the mixing sectiondetermine the configuration of the mixing section. Optimum mixingsections allow for the development of sufficiently long shear areas toattain adequate levels of tension and aspiration. Variations in theconvergence angle from about 2 to 8 and in the mixing length from 0.15to 0.50 in. (0.38 to 1.27 cm.) give satisfactory levels of tension andaspiration. From 6 the over all geometry of the mixing section, aconvergence angle of 4 and the mixing length of 0.2 in. (0.5 cm.) appearoptimum.

The width of the nozzle opening affects both the tension and aspirationdeveloped by the jet devices of this invention. Both of these responsesincrease with decreasing widths of the nozzle openings, although themagnitude of the responses to variations in width become less pronounced-at the wide openings. These facts indicate that the width should bereduced to a minimum, especially since reduction at the low range ismore significant. The minimum width is about 0.006 in. (0.015 cm.),since below this level, it is difficult to maintain the uniformity inthe nozzle openings which is essential for a uniform gas-velocityprofile. Jets with widths above 0.02 in. (0.05 cm.) are relativelyinefficient in the use of primary gas. A preferred width is 0.011 in.(0.038 cm.).

The width of the throat opening in the filament passageway also affectsboth the tension and aspiration developed by the jet. The effect ontension follows the pattern observed with the nozzle opening, that is,the tension increases as the width of the throat opening decreases. Thiseffect is considerably less pronounced at the wider openings.Aspiration, on the other hand, approaches being directly proportional tothe width of the throat opening. The indication from the foregoing isthat the width of the throat should be reduced to a minimum to improvethe tension characteristics and reduce gas consumption. There is a limitto this reduction, however, because it was found that when the ratio ofthe width of the throat opening to the width of the nozzle openingsapproaches 3.5, the gas aspiration becomes unstable and a jet can bemade to change from positive aspiration to blowback simply by touchingthe filament entrance. At ratios below 3.5, blowback occurscontinuously. The Width of the throat opening can be between 0.021 in.(0.053 cm.) and 0.08 in. (0.2 cm.), provided the above-defined ratio ismaintained over 3.5. A prefered throat opening, when the width of thenozzle opening is 0.011 in. (0.038 cm.) is 0.050 in. (0.127 cm.).

The filament passageway diverges from the throat opening to the filamentexit. The purpose of this is to permit the gas velocity to decrease andthereby to reduce the tension on the filaments. As indicated previously,reduction of the tension is desired to permit full relaxation of thefilaments when they reach relaxation temperature. A divergence angle of2 is adequate to obtain the desired reduction in tension.

Since the filament passageway is divergent, the width of the filamentexit will be greater than the width of the throat opening. It has beenfound that tension and aspiration developed by the jet are affected byvariations in the Width of the filament exit in the same general waythat they are affected by the width of the throat opening. There aredifferences, however, which lead to advantageous results. In the firstplace, significant reductions in the width of the filament exit andaccompanying decreases in aspiration can be obtained without inducinginstability, but the filament exit must be maintained sufficiently largeto prevent blowback due to development of excessive back pressure in thefilament passageway. Aspiration can, however, be reduced to very smallvalues without the jet becoming unstable. A second difference is that,at widths above about 0.1 in. (0.25 em.), changes in aspiration inducedby variations in jet exit width are very small. Accordingly, widthsabove about 0.2 in. (0.5 cm.) are not used to control aspiration. Fromthe foregoing it is apparent that the jet exit provides a convenientmeans for regulating the jet aspiration. The width can either beincreased to increase aspiration to a desired value, at the expense oftension, or decreased to reduce aspiration while also obtaining highertension. By adjustment of the width of the throat opening and thefilament exit both the tension and aspiration characteristics of the jetcan be controlled.

The length of the jet from the nozzle openings to the filament exit alsoaifects both the tension and aspiration developed by the jet, and shouldbe from 4 to 36 inches (10 to 92 cm.) but other factors such as spacelimitations or the desired filament residence time from the standpointof heat transfer determine the exact length to be used. In general,increased length increases the tension and decreases the aspiration.These effects were found in tests carried out with a 3-in. (7.6 cm.)wide jet of the design shown in FIGURES 1 through 5 and having a length,as defined above, of 12 in. (30 cm.). Other jet dimensions were asfollows:

Filament-entrance member:

Length (axial) 0.6 in. (1.5 cm.)

Width (narrow dimension,

of passageway X-section) 0.016 in. (0.041 cm.)

Width of nozzle openings 0.016 in. (0.041 cm.) Width of throat opening0.038 in. (0.097 cm.) Width of filament exit 0.080 in. (0.203 cm.)

An 18-in. (46 cm.) length of extension plates was added to give a totallength of 30 in. (76 cm.) and an exit width of 0.140 in. (0.356 cm.). Ameasure of the tension generated by the jet was obtained by inserting a1-in. (2.5 cm.) wide ribbon of a continuous-filament nonwoven web ofpoly(ethylene terephthalate) fibers and determining the tension on theweb at various flows of primary gas (air). Previous studies have shownthat results obtained with the ribbon of nonwoven fabric correspondedclosely with results obtained with a ribbon of 200 filaments evenlyspaced over a span of 2.5 in. (6.4 cm.). The ribbon of nonwoven web ispreferred for use in measuring the tension because of the difficulty inhandling the delicate filaments.

The results, which are summarized below, indicate an increase in tensionof about 30 to 40% with the longer jet, while the aspiration rate withthe longer jet is considerably lower, particularly at the low flow rate.

1 In s.c.f.m.

In addition studies of the eifect of jet length on tension, the ribbonof nonwoven web was inserted at various lengths into the 30 in. (76 cm.)jet. A plot of the total tension on the ribbon against the length ofribbon in the jet indicated low tension values in the filament-entrancemember. This was expected since air velocities are low due to lowaspiration values. The tension increased to a high value in the mixingsection and continued to increase at a much lower rate as the ribbon wasmoved toward the exit. It was found that 54% of the total tension forthe 12-in. (30 cm.) jet and 41%, for the 30-in. (76 cm.) jet, wereproduced in the mixing section. This is a desirable effect for theabove-described web-laydown process since it permits development of aconsiderable part of the stripping tension near the entrance of the jet.The filaments are then subjected to lower tension which makesheat-relaxation possible. Since the level and distribution of thetension can be regulated by modification of the mixing section andthroat opening of the jet, the length can be adjusted to suit theprocess requirements related to relaxation kinetics, rather than tensionand aspiration.

Additional static threadiine-tension measurements were carried with a3-in. (7.6 cm.) wide jet having the following dimensions:

Jet length (overall) 12 in. (30 cm.) Width of filament-entrance member0.020 in. (0.051 cm.) Width of nozzle openings 0.011 in. (0.028 cm.)Width of throat opening 0.050 in. (0.127 cm.) Width of filament exit0.130 in. (0.330 cm.)

The tension developed on a ribbon of 108 nylon monofilaments (l0 denier)(1.1 tex) with a flow of 35 s.c.f.m. (980 liters/min.) of primary airper side of the jet was g. This corresponds to about 0.1 g.p.d. Withanother jet of the same dimensions except that the width of the throatopening was 0.052 in. (0.132 cm.), the tension exerted on a movingstrand of 192 electrostatically-charged poly(ethylene terephthalate)filaments (3 denier; 0.3 tex) was measured by determination of the dragon the filaments as they were passed over Al Si Mag rods attached to astrain gauge. At a primary air fiow of 35 s.c.f.m. (980 liters/min), thetotal measured tension was 64 g., which corresponds to 0.111 g.p.d. Thetension on a strand of 96 filaments was 32 g., thus the tension wasproportional to the number of filaments. This is indicative of goodfilament separation in the jet. In typical operation of the jets of thisinvention with heated primary air to effect heat-relaxation ofpoly(ethylene terephthalate) filaments, air at to 250 C., is introducedinto the two plenum chambers under pressures of about 15 to 40 p.s.i.g.(1.1 to 2.8 kg./cm. It then expands to sonic or supersonic velocitiesthrough the nozzle openings into the mixing section and then into theeifuser section at velocities greater than the velocity of thefilaments, which may be of the order of 4,000 y.p.m. (3,660 m./min.).This high-velocity air imposes the necessary tension on the filaments.The two air streams also create shear zones that entrain air from thefilament entrance member thus providing aspiration for string-up orself-stringing during operation. A suitable level of aspiration forthese purposes is 1 s.c.f.m. per inch of jet width (11 liters/min. percentimeter of jet width). The two air streams also impinge on thefilaments at a high velocity and provide the desirable eifect ofconcentrating a major portion of the total tension in the mixing sectionof the jet.

In addition to the advantage that the slot-jet devices of this inventionconform geometrically to the ribbonlike shape of the filament strandcoming from a drawroll operation, other unexpected advantages resultfrom their use. These include the ability to maintain a higherelectrostatic charge level for a given number of filaments, thuspermitting greater separation of the filaments prior to their laydown asa nonwoven web. Another advantage is that the air-velocity distributionwith slot-jets is so superior that a lower gross stripping tension isrequired than with a round jet (0.08 g.p.d. vs. 0.10). In addition asubstantially different and more desirable laydown pattern is obtainedwith the slot-jet. A flat wide swath replaces the bell-shaped and narrowswath obtained from a round jet. The wide swaths can be more easilyblended to form uniform, wide nonwoven webs. An additional advantage isthat the output from several slot-jets can be blended merely by buttingthe narrow side of one jet to the next, thus forming a uniform curtainof filaments which leads to a uniform nonwoven web. This blending cannotbe obtained with round jets.

What is claimed is:

1. An improved filament-forwarding jet device which comprises a jethousing having mounted therein a filament-entrance member and an eifusermember, each member defining an inlet, a passageway of generallyrectangular cross section, and an exit all in axial alignment, saidfilament-entrance member projecting into the inlet of said effusermember for feeding a bundle of filaments to the etfuser inlet, means forsupplying fluid under pressure including two nozzle openings ofgenerally rectangular cross sectionbetween the filament-entrance memberand the inlet of the effuser member, each having a width of betweenabout 0.006 and 0.020 inch and presenting a fluid-entrance angle of lessthan 16 with the axis of the efluser-member passageway, theefiusermemberpassageway having a throat portion whose width is at least 3.5 timesthat of each nozzle opening, but less than about 0.08 inch, saidfilament-entrance-member passageway having an axial length of betweenabout 0.5 and 1.0 inch, and said etfuser member passageway having anaxial length between the nozzle openings and the filament exit of fromabout 4 to 36 inches.

2. The jet of claim 1 wherein the width of the filamententrance-memberpassageway is between about 0.015 and 0.030 inch.

3. The jet of claim 1 wherein the nozzle opening has a pair of wallsthat converge in the downstream direction at an angle of at least 2.

4. An improved filament-forwarding jet device which comprises a pair offilament-entrance plates terminating in lip portions and a pair ofeffuser plates, each of said pair of plates cooperating with the samepair of end plates to constitute, respectively, a filament entrance andan etfuser member with axially aligned rectangular passageways extendingthrough each of said members, the lip portions of the filament-entranceplates and the vicinal portion of the elfuser plate cooperating todefine a mixing section and two rectangular nozzle openingscommunicating therewith for the introduction of fluids under highpressure, each of said nozzle openings having a width of between about0.006 and 0.020 inch and presenting a fluid-entrance angle of less than16 with the axis of the effuser-member passageway, thefilamententrance-member passageway having a length of between about 0.5and 1 inch, said effuser member passageway having an axial lengthbetween the nozzle opening and the filament exit of from about 4 to 36inches, and the throat portion of the efiuser-member passageway having awidth that is at least 3.5 times that of each nozzle opening but is lessthan about 0.08 inch.

5. The device of claim 4 wherein the lips of the filament-entranceplates and the vicinal portion of the effuser plates are relieved so asto be out of contact with the end plates.

References Cited by the Examiner UNITED STATES PATENTS 2,994,938 8/1961Loveland et al. 28-1 3,055,080 9/1962 Claussen et al. 281 3,081,9513/1963 Dyer et al. 281 X 3,156,752 11/1964 Cope 264345 WILLIAM J.STEPHENSON, Primary Examiner.

1. AN IMPROVED FILAMENT-FORWARDING JET DEVICE WHICH COMPRISES A JETHOUDING HAVING MOUNTED THEREIN A FILAMENT-ENTRANCE MEMBER AND AN EFFUSERMEMBER, EACH MEMBER DEFINING AN INLET, A PASSAGEWAY OF GENERALLYRECTANGULAR CROSS SECTION, AND AN EXIT ALL IN AXIAL ALIGNMENT, SAIDFILAMENT-ENTRANCE MEMBER PROJECTING INTO THE INLET OF SAID EFFUSERMEMBER FOR FEEDING A BUNDLE OF FILAMENTS TO THE EFFUSER INLET, MEANS FORSUPPLYING FLUID UNDER PRESSURE INCLUDING TWO NOZZLE OPENINGS OFGENERALLY RECTANGULAR CROSS SECTION BETWEEN THE FILAMENT-ENTRANCE MEMBERAND THE INLET OF THE EFFUSER MEMBER, EACH HAVING A WIDTH OF BETWEENABOUT 0.006 AND 0.020 INCH AND PRESENTING A FLUID-ENTRANCE ANGLE OF LESSTHAN 16* WITH THE AXIS OF THE EFFUSER-MEMBER PASSAGEWAY, THEEFFUSERMEMBER PASSAGEWAY HAVING A THROAT PORTION WHOSE WITH IS AT LEAST3.5 TIMES OF EACH NOZZLE OPENING, BUT